SPOKANE , Wash.  In his 16 years as an assistant here, Bill Grier had a front-row seat to watch any number of outstanding Gonzaga men’s basketball teams.

“This is the best one,” he said Saturday.

That was his opinion even before the third-ranked Bulldogs reaffirmed it with a 81-50 rout of Grier’s USD Toreros, clinching at least a tie for the West Coast Conference regular-season championship and the No. 1 seed in the league’s postseason tournament.

It also concluded a disappointing Northwest swing for the Toreros (13-16, 6-8 WCC) that began Thursday at Portland with a missed opportunity to take a step toward a .500 season.

This one was a bitter reversal of a meeting with the Zags in San Diego, where the Toreros had a shot to win at the buzzer.

“I’m sure they wanted to come out and send a message early,” said USD senior Chris Manresa. “That’s what they usually do in this building. I just wish we would have fought back harder.”

It took less than eight minutes for the Bulldogs (27-2, 14-0) to build a 17-6 lead that never again dipped under double digits, and the attack came from all angles: rim-rocking dunks by Elias Harris, transition drives by Kevin Pangos (who led the Zags with 18 points) and Gary Bell and 3-pointers by Harris and 7-foot Kelly Olynyk.

The Toreros’ offense had but one dimension: Manresa, who scored 19 points on 5-of-6 shooting and a knack for getting to the foul line against Gonzaga’s talented big men, but had no help from the perimeter.

That included leading scorer Johnny Dee managing just six shots and four points while being hounded by Bell.

“Early, we had some good looks that didn’t go down and I think our guys got really frustrated,” said Grier, whose USD teams are winless in six tries at the McCarthey Athletic Center. “We lost all semblance of what we were trying to do.

“When you take a quick one against this team, they’re laying it in or dunking it at the other end. They hurt us big time in transition, but a lot of that had to do with their defense and our offense.”

Gonzaga shot 57.7 percent from the field in the first half, which ended with the Zags up 37-23, and blew open the game by making nine of their first 10 attempts after intermission.

But the Bulldogs were even more efficient on the other end. USD shot just 29 percent in the second half and 36 percent for the game — the fifth straight opponent Gonzaga has held under 37 percent. And after outrebounding Gonzaga by six in San Diego, the Toreros were crushed on the glass, 38-22.

“I thought we did an unbelievable job sticking to our assignments,” said Gonzaga coach Mark Few, “and playing with great energy to finish off possessions.”

That was particularly evident in a 17-2 surge five minutes into the second, during which the Toreros turned the ball over three times, had two shots blocked and missed three rushed 3-pointers.

Manresa was disappointed the Toreros didn’t muster more aggression in “such a great basketball environment.”

“It was the last time for me to play in this building,” he said, “so why not be aggressive and go at them? Big crowd, big emotion — that’s what college basketball is all about. It should give you energy, but we didn’t match theirs.”